Production of condensation products of carbamides and formaldehyde



Patented Dec. 15, 1931 UNI ED STATES PATENT OFFICE WILHELM PUNGS, mm. EISEWII AND J'dHANN KUC KINBUCH, OI LUD'WIGB- EAII'EN-ONeTHE-BHINE, GERMANY, ASSIGNOBS TO I. G. FABBENINDUSTBIE AKTIEN- GEBELLSO HAI'I, OF FBANKIORT-ON-TEEKAIN, GERMANY, A CORPORATION OF GERMANY PRODUCTION OI CONDEN'SATION PRODUCTS CARBAKIDES AND IOBMALDEEYDE llo Drawing. Application filed June 12, 1828, Serial No. 370,453, and in Germany June 85,

The present invention relates to the manufacture and production of condensation prod ucts'of carbamides and formaldehyde. Various rocesses for the production of con- 6 densation products by a condensation of urea or of another carbamide with formaldeh de are known in the art. The condensation as been performed in the presence or absence of water or also in the presence of organic solvents dissolving the reaction products. In-.

or polymers thereof prepared in organic media comprising solvents with alcoholic radicles such as monoor poly-hydric aliphatic aromatic or hydroaromatic alcohols or their derivatives such as esters or ethers, containing at least one free alcoholic group with liquids which have a precipitating actio ron the carbamide formaldehyde condensation products, or b carrying out the original condensation in iquids in which the condensa tion product obtained does not dissolve, but in which it remains suspended in a solid form, as for example in dioxane (diethylene 1.4 dioxide) or its homolo es, alkyl ethers of phenols, such as aniso di-alkyl ethers of glycols or in hydrocarbons or mixtures containing. a substantial proportion thereof, such I as turpentine oil.

The precipitants are for the most part the same substances as those in which the aforesaid condensation without dissolution of the condensation products can be carried out, for example, aliphatic, aromatic and hydroaromatic hydrocarbons, and ethers, preferably those of a low boiling point, of the type ROR in which R andR may be alkyl or aryl radicles, but any other liquid organic compound showing a precipitating action maybe employed. In contrastto the ethers containing free hydroxyl groups mentioned above the ethers of the ty e R-O-R' will be referred to as neutral et crs.

It is preferableto carry out the precipita-' tion or condensation in such a manner,for

example by employing an ample amount of precipitant that t e condensation products are obtained in a finely pulverulent state, in which state they can be easily and completely freed from the adhering solvents or suspending agents employed in the condensation y thorough washm with easily volatile organic liquids in whic the condensation products are not soluble, and they may then be easily dried. According to this process, condensation roducts of carbamides and formaldehy e are obtained which do not contain organic solvents, free formaldehyde or moisture.

The products obtained by recipitating after the condensation are solu le in many organic solvents, especially in organic compounds which contain one or more free hyethers of a higher molecular weight, such as anisol, and esters, such as butyl acetate.

' Carbamide formaydehyde condensation products prepared in different solvents differ in their'properties, in some cases to a considerable degree and in particular as regards stability to water. a

Thus, for example, products obtained by a condensation in methyl or eth 1 alcohol, in mono ethers ofglycol or also in polyhydric alcohols, are rather sensitive to water. On the other hand products obtained from reaction mixtures containing higher monohydric alcohols, and in articular those which contain 4, 5 and 6 car n atoms, or benzyl alcohol are scarcely attacked b water at all, but they have .the 'drawbac s that in working them up as lacquers or artificial masses they frequentl still retain the smell of the solvent, the volatility of which is too smallin some cases for an easy and thorough removal there- T These drawbacks can be avoided in a simple manner. It has been found that the properties of the recipitated condensation products acquired by the employment of the said higher alcohols in the condensation process are retained when dissolving them in another solvent. Thus in order to prepare a la uer which will produce coatings capable of resisting water when dried, a caramide formaldehyde condensation product is prepared in a higher monohydric alcohol for example according to the aforesaid applications and is precipitated from the solution by the addition of a suitable precipitant for example eth lether, and then is redissolved in a liqui having a suitable volatility and, preferably only a slight smell, for example glycolmonomethyl ether. Instead of one solvent, mixtures of several solvents which may also contain limited quantities of water, may be employed. Even a small addition of water to the solution of a precipi tated condensation product of a. carbamide and formaldehyde in a solvent which is miscible with water, has no influence on the properties of the final products made therefrom, such as lacquers. The choice of solvent is made according to the desired velocity of drying of the lacquer and the like and ac cording to the other additional substances, such as cellulose esters, softening agents and the like which are also to be dissolved.

The'pulverulent condensationroduct of carbamldes and formaldehyde obtained by precipitation, or by condensation in a liquid in which the condensation roduct is not soluble can be pressed prefera ly at an elevated temperature into transparent homo eneous pieces which are free from moisture, ormaldehyde and organic solvents and which consequently do not exhibit the phenomena of a ing, such for example as cracks and the li e, if desired with the addition of fillers, colouring materials, softening agents and the like.

In the place of a urea and formaldehyde the corresponding monoor di-methylol may be employed which can be obtained b condensing the urea chosen and formal ehyde under mild conditions, preferably with the aid of an alkaline agent, which methylol compounds are therefore considered as equivalents of urea and formaldehyde.

The following examples will further illustrate the nature of the invention but the invention is not restricted to these examples. The parts are by weight.

Example 1 9000 parts of amylalcohol heated to 110 C. The mixture is then stirred and after the reaction, the clear solution is neutralized by adding 100 parts of tertiary sodium phosphate.

200 parts of this solution are stirred at ordinary temperature with to 10 times the wei ht of petroleum ether of a boilin point of a out 40 centigrade. After stirrlng for a short time, the whole is allowed to settle and the supernatant liquor drawn oil; the precipitated condensation product is then treated with 250 parts of ethyl ether, vigorously stirred for some time and filtered off. The fine powder of the precipitated product is then washed several times with ethyl ether and then dried in vacuo at 50 centigrade. The urea formaldehyde condensation product so obtained is dissolved at about room temperature in n-propyl alcohol while stirring so that a. 40 per cent solution is obtained, and this solution diluted with ethyl alcohol to produce a per cent solution.

A quickly drying lacquer having only a slight smell is obtained, coatings of which are scarcely attacked by water.

A condensation product of thiourea and formaldehyde may be employed instead of the aforesaid urea formaldehyde condensation product.

Example 2 50 parts of an a proximately per cent solution of a condhnsation product of d1- methylol thiourea preparedin benzyl alcohol are stirred for a short time with 500 parts of-ethyl ether. After allowing the precipitated condensation roduct to settle the supernatant li uid is awn off, the precipitate again stirre with Iparts of ethyl ether for some time and furt er worked up as described in Example 1. The finely powdered urea formaldehyde condensation product so obtained is dissolved while stirring in glycol monoethyl ether at about 80 centrigrade, so that a 50 per cent solution is obtained, and this is diluted with ethyl alcohol to produce a 20 per cent solution. The laquer so obtained gives clear coatings which are stable to water.

If desired cellulose esters such as cellulosenitrate and softening agents may also be incorporated in this lacquer.

Example 3 .360 parts of dimethylolurea are made into a fine suspension in 500 parts of dioxane. The suspension is then heated to 85 centigrade, treated with 4 parts of oxalic acid,and maintained at the same temperature while stirring until the splitting off of water and formaldehyde is completed. The finely powdered condensation product is then freed from dioxane by filtration, washed several times with ethyl ether and dried as described in Example 1. The condensation may be carried out for example in oil of turpentine instead of in dioxane.

The fine wder obtained may be pressed in moulds un er a pressure of about 6.5 tons per square inch, and at from 100 to 110 centigrade. After pressing for 5 minutes the transparent homogeneous pressed ieces may be taken from the mould while still hot without a risk of distortion or crackin of the moulded pieces being incurred. 'Ehe pulverulent products obtained in Examples 1 and 2 ma also be employed-instead of the condensatlon product prepared in dioxane.

Example 4 100 parts of urea are dispersed in 500 parts of a commercial aqueous solution of formaldehyde together with 5 parts of aqueous 50 per cent caustic potash solution the tempera ture being kept at room temperature by cooling. After some time an amorphous white product constituting an anhydride of two molecular proportions of dimethylol urea, slowly separates from the solution and after 24 hours the roduct is filtered off and washed with ethyl a cohol and ethyl ether. 90 parts of the product are then heated to 90 C. while stirring to ether with 135 parts of iso-butyl alcohol an40 parts of a 5 per cent ethyl alcoholic solution of urea nitrate untilthe solution has become clear. The solution is then neutralized by stirrin it with '10 parts of tertiary sodium phosp ate and filtered after cooling.

50 arts of this solution are then stirred with mm 250 to 500 parts of ethyl ether and treated as described in Exam le 1. lhe powder obtained is then resse into moulds at from 100 C. to 110 at a pressure of 1000 kilograms per square centimetre. The resul ing masses are similar to those obtainable in accordance with the rocess described in Example 3. The recipitated product can be employed also or the manufacture. of lacquers for example according to Examples 1 and 2.

We claim:

1. In the production of resinous condensation products of carbamides and formaldehyde 1n the absence of water the step of add-- ing to the reaction mixture at any stage a quantity of an organic liquid in which the condensation products are insoluble suflicient ucts.

2;; The process for the production of resinous condensation products of carbamides and formaldehyde which comprises condensinga carbamide and formaldehyde in an anhydrous a uantity of an organic liquid, in which the resinous condensation products are insoluble, sufiicient to precipitate the resinous conden sation products.

3. A modification of the process claimed in claim 2 which consists in replacing urea and formaldehyde by a methylol urea.

4:. The process for the production of resinous condensation products of carbamides and formaldehfyde which comprises condensing a urea and ormaldehyde in an anhydrous organic solvent comprisin an alip atic alcohol, until a resinous con ensation product is formed and adding to the solution of the resinous condensation roduct obtained a quantity of an organic iquid, in which the resinous condensation roduct is insoluble, sufficient to precipitate t e resinous condensation roduct.

5. 1e process for the production of resinous condensation products of carbamides and formaldehtyde which comprises condensing a urea and ormaldehyde in an anhydrous organic solvent comprisin an aliphatic alcohol, until a resinous con ensation product is formed and adding to the solution obtained a quantity of ethyl ether suficient to precipitate the resinous condensation product from the said solution.

In testimony whereof we have hereunto set our hands.

WD'JHELM PUNGS.

KARL EISENMANN.

JOHANN KUQHENBUCH.

' to precipitate the resinous condensation prod 

